Conventionally, as an electrode material for use in various secondary batteries such as a lithium secondary battery, various electrode materials having a core-shell structure in which coating made of a conductive substance is formed on the surface of an active material core made of oxides of metals such as lithium, manganese have been proposed. Moreover, as coating made of a conductive substance, the production of an electrode material coated with polymer such as polyaniline by polymerizing a polymeric compound at the surface of active material core particles is also known (for example, refer to Patent Documents 1 to 3).    [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2001-118570    [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2002-358959    [Patent Document 3] Japanese Examined Patent Application Publication No. 2007-522619